The vapor phase nitration of benzene and toluene, and halogenated derivatives thereof, is known in the art. By way of illustration, U.S. Pat. No. 4,618,733 discloses the vapor phase nitration of aromatic compounds, notably chlorobenzene, with nitric acid in the presence of metal oxide catalyst and a sulfur trioxide catalyst. This patent discloses at column 7, lines 48-53 the use of eutectic salt baths as a medium to maintain the reactor surfaces at a relatively constant temperature and to conduct heat from the reactor. The reaction time disclosed in this patent for the illustrated batch reactions is long, typically between 3 and 7 hours. Moreover, the equipment and the catalyst requirements for this system are relatively more complex than might be desired.
New, simpler nitration methods for nitrating aromatic hydrocarbons, preferably with fast reaction times, would be highly desirable in the industry.